Yanjiang Bian

A highly selective and ratiometric fluorescent sensor for relay recognition of zinc(II) and sulfide ions based on modulation of excited-state intramolecular proton transfer

A new fluorescent 2-(2′-aminophenyl)benzimidazole derivatized sensor BMD was designed and synthesized. In CH3CN/H2O (2 : 8, v/v, HEPES 10 mM, pH 7.4) solution, sensor BMD displays two emission bands and exhibits a highly selective and ratiometric response to Zn2+ ions with a distinctly longer-wavelength emission blue shifted through the inhibition of the excited-state intramolecular proton transfer (ESIPT) process. BMD can clearly discriminate Zn2+ from Cd2+ and other metal ions. Moreover, the in situ generated BMD-Zn2+ solution exhibits a highly selective and ratiometric response to S2− among various anions and thiol-containing amino acids via Zn2+ displacement approach, which results in a revival of the ESIPT phenomenon of free BMD. These results demonstrate that BMD can serve as a ratiometric sensor for sequential recognition of Zn2+ and S2− in aqueous solution through inhibition and turn-on of ESIPT process.

Multi-analyte, ratiometric and relay recognition of a 2,5-diphenyl-1,3,4-oxadiazole-based fluorescent sensor through modulating ESIPT

A new two dipicolyl amine (DPA) dangled 2,5-diphenyl-1,3,4-oxadiazole derivatized sensor L has been designed and synthesized. Sensor L displays excited state intramolecular proton transfer (ESIPT) properties in buffered water solution (HEPES 10 mM, pH = 7.4). L shows highly selective and ratiometric fluorescence responses to Zn2+ in a 1 : 2 binding ratio. Fluorescence spectra and 1H NMR studies demonstrate that L binds Zn2+ ions through its amide form, which promoted the ESIPT emission enhancement. The in situ generated L–2Zn2+ complex can serve as a relay recognition sensor toward PPi and S2− via further complexation and Zn2+ sequestering processes respectively. Thus, multi-analyte and relay recognition of L through modulating ESIPT has been achieved.

A water-soluble highly sensitive and selective fluorescent sensor for Hg2+ based on 2-(2-(8-hydroxyquinolin)-yl)benzimidazole via ligand-to-metal charge transfer (LMCT)

A water-soluble fluorescent sensor (L) based on 2-(2-(8-hydroxyquinolin)-yl)benzimidazole has been synthesized and characterized. Sensor L displays highly selective and sensitive recognition of Hg2+ with a fluorescence “ON–OFF” response in buffered aqueous solution (1% dimethyl sulfoxide (DMSO), Tris–HCl 10 mM, pH = 7.4). X-ray crystal structure of the L–Hg2+ complex reveals that the oxygen and nitrogen atoms of 8-hydroxyquinoline and the imine N atom of the benzimidazole unit (N1) bind Hg2+ through a 1 : 1 binding stoichiometry. The fluorescence quenching mechanism is qualitatively evaluated by quantum chemical calculations which show that the fluorescence quenching phenomenon is caused by ligand-to-metal charge transfer (LMCT) in the excited state.

A new hydroxynaphthyl benzothiazole derived fluorescent probe for highly selective and sensitive Cu(2+) detection.

A new reactive probe, 1-(benzo[d]thiazol-2-yl)naphthalen-2-yl-picolinate (BTNP), was designed and synthesized. BTNP acts as a highly selective probe to Cu(2+) in DMSO/H2O (7/3, v/v, Tris-HCl 10mM, pH=7.4) solution based on Cu(2+) catalyzed hydrolysis of the picolinate ester moiety in BTNP, which leads to the formation of an ESIPT active product with dual wavelength emission enhancement. The probe also possesses the advantages of simple synthesis, rapid response and high sensitivity. The pseudo-first-order reaction rate constant was calculated to be 0.205min(-1). Moreover, application of BTNP to Cu(2+) detection in living cells and real water samples was also explored.

A novel benzothiazole-based enaminone as a fluorescent probe for highly selective and sensitive detection of CN−

A novel benzothiazole derived enaminone BTP as a fluorescent probe for CN− recognition has been developed. In DMSO/H2O (95/5, v/v, HEPES 10 mM, pH = 7.4) solution, BTP exhibits high selectivity toward CN− among various anions through colorimetric and fluorescence dual channel changes. On treatment with CN−, BTP displays a blue shifted fluorescence enhancement and a naked eye observable color change from orange to yellow green. Moreover, the CN− sensing event possesses an excellent anti-interference ability over other anions. Sensing mechanism investigations prove that the CN− recognition process undergoes a typical nucleophilic addition of CN− to the enaminone formed BTP. Simple test paper experiments evidenced the practicability of BTP for CN− detection.

A fluorescent sensor based on binaphthol-quinoline Schiff base for relay recognition of Zn2+ and oxalate in aqueous media

AbstractTo develop an effective fluorescent chemosensor for relay recognition of Zn2+ and oxalate, a new fluorescent sensor based on binaphthol-quinoline Schiff base L1 was designed and synthesized. In DMSO-H2O (1/1, v/v, HEPES 10 mM, pH = 7.4) solution, L1 exhibits highly selective fluorescence turn on response to Zn2+ over other metal ions. The Zn2+ recognition event is barely interfered by other coexisting metal ions except Cu 2+, Co 2+ and Ni 2+. The in situ generated L1-Zn2+

Rapid and highly selective relay recognition of Cu(II) and sulfide ions by a simple benzimidazole-based fluorescent sensor in water

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Relay recognition by modulating ESIPT: A phenylbenzimidazole derived sensor for highly selective ratiometric fluorescent recognition of Zn2+ and S2− in water

complex was further used as a chemosensing ensemble for oxalate detection. The complex L1-Zn2+ displays high selectivity to oxalate with significant fluorescence quenching through Zn2+ ion displacement approach. In addition, application of L1 for imaging of Zn2+ and oxalate in living HeLa cells was also examined. Graphical AbstractA new binaphthol-quinoline Schiff base-based fluorescent sensor L1 exhibits highly selective relay recognition of Zn2+ and oxalate through fluorescence “off-on-off” functionality in DMSO-H2O (1/1, v/v, HEPES 10 mM, pH = 7.4) solution.